The conditional medaka mutation eyeless uncouples patterning and morphogenesis of the eye

In early vertebrate eye development, the retinal anlage is specified in the anterior neuroectoderm, During neurulation, the optic vesicles evaginate f rom the lateral wall of the prosencephalon. Here we describe the temperatur e-sensitive mutation eyeless in the Japanese medakafish. Marker gene analys is indicates that, whereas, specification of two retinal primordia and prox imodistal patterning takes place in the mutant embryo, optic vesicle evagin ation does not occur and subsequent differentiation of the retinal primordi a is not observed. The mutation eyeless thus uncouples patterning and morph ogenesis at early steps of retinal development. Temperature-shift experimen ts indicate a requirement for eyeless activity prior to optic vesicle evagi nation, Cell transplantation shows that eyeless acts cell autonomously.